Establish a performance baseline
Planning involves establishing baseline performance thresholds — called quality-of-service (QoS) rules — using historical data, estimates of how existing services will grow, and anticipated demand for new services.To determine if your plan is working, you’ll need to measure current network behavior. Such metrics include the traffic generated at certain interface points and the load levels of trunks and devices.

This is how network administrators monitor and manage network conditions. When conditions are out of whack, an alert is generated.

These alerts can indicate an emerging issue, such as a need for additional resources, or a serious problem, such as load levels so high that network and/or application performance has been impacted.

Plan for failure modes
Inevitably, your network’s performance will sometimes fall short of its optimal state. So you’ll need to define ‘failure modes’ that maintain a balance among business goals when there’s congestion or some sort of failure. This sort of planning is especially important if your organization operates a network that delivers multimedia services (voice and/or video as well as data) because each medium has different tolerance for out-of-specification network operations — and different economic importance to your business.